Telephone system



Aug. 7,, 1923.

E. E. HINR ICHSEN TELEPHONE SYSTEM Filed Dec. 18. 1919 I J /n vmor:

Edward E H/hr/Ch 56/7 Patented Aug. 7, 1923' tJNlTED STATES PATENT OFFICE.

EDWARD IE. HINBICI-ISEN, OF NEW YORK, N. Y., ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION 015 NEW YORK.

TELEPHONE SYSTEM.

Application filed December 18, 1919. Serial No. 345,714.

new and useful Improvements in Telephone Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone systems and more particularly to systems in which connections are established under substation control.

In a previously filed copending application, of Charles L. Goodrum Serial No. 359,327, filed February 17, 1920, there is disclosed a full relay automatic telephone system to which reference is made for a full and complete disclosure of the present invention.

An object of the present invention is to provide an improved circuit arrangement for performing the various functions incident to the final connections of a calling line to a called line.

In accordance with this object,a pair of relays are provided as a means of testing the busy or idle condition of the called line and which operate accordingly in a different sequence, at the same time, controlling in accordance with the sequence in which they are operated, other circuits to perform the necessary switching functions such as connecting ringing current to the called line, connecting busy tone to the calling line, completing the conversational circuit be tween the calling line and the called line, etc.

The drawing diagrammatically illustrates the preferred embodiment of the invention. The calling substation is shown with means indicated to connect it to the circuit in which the invention resides and means indicated for extending the circuit to and establishing a connection with a called telephone line. For a full explanation of the manner in which the indicated connecting means is operated, reference may be had to the before-mentioned application of Charles L. Goodrum, Serial No. 359,327, filed February 17, 1920.

When the subscriber at substation 1 removes his receiver from its hook, he causes his line relay .2 to become energized which,

in turn, causes the energization of two relays 3 and 4. The relay 3 connects the line from substation l to a transfer circuit 5 and the relay 4.- connects the transfer circuit 5 to a trunk circuit in which the various functions of the connector switch are performed. This trunk circuit will be referred to 'by its details, since it occupies practically the whole of the drawing.

Upon the operation of the relays 3 and 4, the substation line is connected to the relay 6 which becomes energized through its two windings and the substation loop, and by pulling up its armature causes the energization of afirst slow relay 7. This relay quickly but releases the attraction of its attracts its armatures them slowly. Upon left-hand armature, it places a ground on and awaiting the sending of impulses from the substation 1.; We will assume that the called substation is 12 and we will so number it 12. The subscriber at substation 1 now manipulates his dial switch 10 to send a single impulse. This impulse is in the form of an interruption of the circuit including relay 6, whereupon relay 6 retracts its armature momentarily. During this momentary retraction of its armature, relay 6 completes a circuit from grounded battery, winding of relay 14:, winding of relay 13, front contact and right-hand armature of relay 7, back contact and outer left-hand armature of relay l1 and then to ground at the back contact and armature of relay 6. Relay 13 upon energizing closes a locking circuit extending through its own arma-\ ture and back contact of relay 15, normal contact of the inner right-hand armature and winding of relay 16,.conductor 8 to ground at the left-hand armature and contact of relay 7 Relay 16 attracts its armatures and is so adjusted that the normal contact of the inner right-hand armature will break before contact is made to the outer ri lit-hand armature. As soon as this contact is broken, relay 13 becomes deem ergized and by opening its circuit at its armature prevents the current from flowing through its winding, after the outer righthand armature and contact of relay 16 are closed. Relay 16 looks up from grounded battery, conductor 17, inner right-hand armature and alternate contact of relay 16, the winding thereof to ground on conductor 8.

After a. slight interval, relay 1a retracts its armature. When this takes place, a circuit is closed from ground, the normal contact of the armature of relay 14,-, conductor 18, left-hand armature and back contact of relay 19, outer left-hand armature and front contact of relay 16, winding relay to battery and ground. Relay 15 iinds a substitute circuit through its left-hand armature and front contact and locks up to the ground on the conductor 8. Through its right-hand armature, it switches the counting relay circuit from the upper row of counting relays to the lower row of counting relays.

The subscriber now manipulates his dial switch 10 to send a series of two impulses which are in the form of two interruptions of the line circuit. Thus, the armature of relay 6 is retracted twice. Upon the first retraction, the circuit for relays 13 and 1e heretofore described is closed, whereupon both become energized. At the end of the first interruption, relays 14- and 13 find a circuit from grounded battery, windings oi relays 14: and 13, armature and front contact of relay 13. right-hand armature and 'front contact of relay 15, normal contact of the inner right-hand armature of relay 19, winding of relay 19, conductor 8, lefthand armature and front contact of relay 7 to ground- Relay 19 attracts its an matures and as soon the normal contact of its inner right-hand armature-is opened, relay 13 becomes deenergized. Relay 14 however, being slow-toaelease, does not reftract its a mature until after the series of impulses, as a whole, has terminated. This happens at the end of the next interruption. During this next interruption relay 13 is again energized. Relay 13, in attracting its armature, extends a circuit to the winding oifrelay 20, but relay 20 being short-circuited by. the ground at the back contact of the armature of relay 6, does not attract its armatures at this time. "At the end or the interruption when relay 6 attractsits armature and holes it in its attracted position, relay 20 becomes energized ove'ra circuit similar to that here tofore traced, now extending through the front contact and outer riglrhand armature of relay 19, the normal. contact of the inner right handarmature 01' relay 20, winding of relay 2O to ground on conductor 8. When relay 2O attracts its armature, it breaks this circuit and relay 13 becomes deenergized. After a short interval, relay 1% becomes deenergized and closes a circuit from ground, the normal contact of its armature, conductor 18, the left-hand armature and front contact of relay 19, left-hand armature and front contact of relay 20, the left-"rand armature and back contact of relay 21, conductor 22, winding of relay 23 to batteryand ground (not here shown) and in parallel therewith through the left-hand armature and front contact of relay 1 9, the inner left-hand armature and front contact of relay 16, the left-hand armature and bacl: contact of relay 24, conductor 25, winding of relay 26 to battery and ground (not here shown). Relays 23 and 26 become energized and lock up to the ground on conductor 8. 7

Relay 14, during its energizcation, closes a circuit from ground, the alternate con tact of its armature to the winding of relay 2?, battery and ground. Relay 27 becomes energized in this circuit and being of the slow-releasing type does not immediately release its armatures when relay it becomes deenergized as hereinbefore described. Upon the attraction of their armatures by relays 23 and 26, the connector circuit is extended to the called line 12.

At this time, a test is made of the idle or busy condition 01": he called line. This test consists in connecting thelett-hand winding of relay 11 into a circuit extending through the normal contact of its inner left-hand armature, the front contact and left-hand armature of relay 27, the lower armatures and contacts of relays 23 and 26, to the winding of relay 28. If the line is idle this circuit will be as described and since the potential connected to the winding of relay 11 is the same as the potential connected to the winding of relay 28, neither. relay 11 nor 28 will immediately become energized. After a short interval, relay 27 retracts its armatures whereupon the relay 28 is energized over a circuit from grounded battery, its own winding, the lower contacts and armatures of relays 26 and 23, conductor 29, left-hand armature and back con-- tact of relay 27, right-hand winding of relay 11 to the ground on conductor 8. Relay 11 becomes energized in this circuit and through its inner left-hand armature and alternate contacts locks up to the ground on conductor 8. By means of its inner-righthand armature, it extends a circuit from ground to the right-hand armature and back contact of relay 27, winding of relay 30 to battery and ground. Relay 30 becomes energized in this circuit and through its armatures and contacts closes a circuit from the armatures of ringing relay 31 to the line of substation 12. Thereupon, ringing current, supplied from a source indicated at 32, is applied over a circuit extending through the right-hand winding of relay 31, the back contact and outer right-hand armature of relay 31, the front contact and outer right-hand armature of relay 30, the middle armatures and contacts of relays 23 and 26,

substation loop including the call bell at substation 12, the upper contacts and armatures of relays 26 and 23, the inner righthand armature and contact of relay 30, the inner right-hand armature and back contact oi relay 31 to ground. Ringing current fiowing over this circuit is sufiicient to operate the call bell at the substation 12, but is insuiiicient to cause the operation of relay 81. When the subscriber at substation 12 in answer to the summons of his bell, removes his receiver from the hook, he so reduces the resistance of the line that the flow of ringing current is augmented to the point where relay 31 becomes energized. Relay 31 thereupon locks up through its left-hand Winding and its left-hand armature and contact to ground on conductor 8 and at the same time cuts oil the ringing current fromthe called line and completes the conversational circuit between the calling and called lines.

Talking current is supplied to the called line through the windings of battery teed coil 33.

At the end of the conversational period, the calling subscriber replaces his receiver on its hook and causes the disestablishment of the entire connection by causing the deenergization of first relay 6 and then relay 7. Relay 7, through its left-hand armature, removes ground from conductor 8 where upon all relays locked to this conductor will be deenergized and thus leave the connection in its normal state.

Going backto the point where the test of the called line is made, it will be supposed that the called line 12 is busy. In this case, a ground is found on the lower armature of relay 26. This ground will cause the energization of relay 11 through its left-hand winding, whereupon it will lock up to the ground on conductor 8 through its left-hand armature and alternate contact. Through its inner right-hand armature and front contact, it will cause relay 27 to remain energized by virtue of a locking circuit extending from ground, through the right-hand armature and front contact of relay 27, and the winding there of to battery and ground. By causing relay 27 to remain energized, it insures the nonoperation of relay 30. Relay 11 through its outer right-hand armature connects a source of busy current through the left hand armature and contact of relay 30, the left-hand winding of battery teed coil 33 to ground, whereupon through inductive action, the busy tone is transmitted to the calling substation. The calling subscriber recognizing the tone, may hang up his rerelay and means responsive to thebusy condition of said line for energizing said first relay prior to the deenergization of said second relay.

2. In a telephone system, a telephone line, a testing point associated therewith, means for determining the busy or idle condition of said line comprising a plurality of relays, a first relay being connected to said testing point through the contacts of a second relay, means for transiently energizing said second relay to make a test of said line, means responsive to the idle condition of said line for energizing said first relay incident to the deenergization of said second relay and for applying ringing current to said line and means responsive to the busy condition of said line for energizing said first relay priorto the deenergization of said second relay.

3. In a telephone system, a calling telephone line, a called telephone line, means for interconnecting said lines, a testing point associated with said called telephone line, means for determining the busy or idle condition of said called line,comprising a plurality of relays, a first relay being connected to said testing point through the contacts of a second relay, means for transiently energizing said second relay to make a test of said called line, means responsive to the idle condition of said line for energizing said first relay incident to the deenergization of said second relay and means responsive to the busy condition of said line for energizing said first relay prior to the energization of said second relay and for connecting busy tone to said calling line.

4. In a telephone system a telephone line, a testing point associated therewith, means for testing the busy or idle condition of said 7 line comprising a plurality of relays, one of said relays being provided with two windings, each connected through the contacts of a second relay to said testing point, means for transiently energizing said second relay to make a test of said line, means including one of said windings of said first relay responsive to the idle condition of said line for energizing said first relay and means innected to said testing point through the contacts of said slow to release relay, means responsive to the idle condition oi said. lino for energizing said quick relay When said. slow to release relay is deenergized and means responsive to the busy condition of said line for energizing said quick relay When'said slow to release relay is energized.

6. In a telephone system, a telephone line, a testing point associated therewith, means for determining the busy or idle condition of said line comprising a plurality of relays, a first relay being connected to said testing); point through the contacts of a second relay, means for transiently energizing said second relay to make a test of said line, means responsive to the idle condition of said line for deenergizing said second relay and thereupon energizing said first relay, and means responsive to the busy condition of said line for maintaining said second relay energized and for energizing said first relay.

7. In a telephone system, a telephone line, a testing point associated therewith, means for testing the busy or idle condition of said line comprising two relays, both of said relays being ener ized' in response to the busy condition oi: said line and only one being energized in response to the idle condition of said line, a circuit for controlling; the application of ringing current to said line controlled by the said two relays under the idle condition, and a circuit for controlling the application of busy tone to the line of a controlling subscriber under the busy condition.

In Witness whereof, I hereunto subscribe my name this 15th day of December A, D.

EDWARD n. HINRIOHSEN. 

